The prior art includes a "window shade" deployed space-fed phased array radar antenna which is particularly suited for use in space. The rolled antenna is advantageous because it minimizes storage space aboard a spacecraft. When the spacecraft achieves selected orbit, the antenna is deployed and the "window shade" structure becomes unrolled to a fully expanded operative condition. Such an antenna consists of a low-power RF feed which illuminates a lens aperture membrane. Active transmit/receive (T/R) modules in the aperture membrane receive radar pulses from the ground, amplify them, and perform beam-steering phase shifts so that the signal may be re-transmitted toward a target of interest in space. The reflected energy is received in reverse order, being amplified by the T/R modules then focused back onto the space feed. Radar processors and supporting subsystems are located in a bus at the base of a feed mast. A tensioned three-layer membrane constitutes the aperture and provides a very lightweight, yet sufficiently flat, aperture plane. Array flatness requirements for the space-fed approach are less severe than for corporate-fed approaches by an order of magnitude. The membrane aperture can be rolled up onto a drum resulting in a simple, compact, and repeatable method for deployment/retraction of the antenna.
When being launched into space, in order to assure that a multiple layer membrane structure remains neatly wrapped about a drum when subjected to high "G" forces of launch, means must be found for supporting the membrane structure on the drum so as to prevent the various wrapped layers from sliding relative to one another and unraveling. Such unraveled windings of the multi-layer membrane will jam a deployment mechanism which becomes operative when an appropriate orbit is reached.